Comment: No diplomas please, this system will serve us well for another 50 years

For many young people, today will be one of the best of their lives.

The A-level results are better than ever, with even more of the coveted A grades awarded. Yet alongside the cheering, students may have heard murmurings that the exam is not what it should be.

The trouble is that young people have been doing just too well. With more than a quarter of the entries gaining an A, the exam has not been distinguishing sufficiently at the top to enable the leading universities to allocate their places fairly. This has led to calls for Alevels to be radically changed - or scrapped altogether.

Some say the exam has become too easy. Yes, the pass rate has risen every year for the past 26, but there are five levels of pass, and the top grade has become ever more important. For courses from September there will be tougher questions and a new A* grade.

The pass rates leapt and girls opened up a big lead when A-levels were broken up into six units in 2002, and there are some who would like to see a return to end-of-course examinations. But there are those - including the Government, so it is said - who would like to see the end of A-levels.

Over the past 10 years we have seen substantial falls in subjects such as modern languages, physics, geography and economics, with the growth being in fields such as media studies and the expressive arts. Some of the leading schools and universities argue for imposing the academic breadth of the international baccalaureate.

The Government, however, is concerned about the difference in prestige between academic and vocational courses, and wants a qualification in which everyone has to do skills training. But the problem with diplomas is that they are all or nothing. The great strength of Alevels is that they enable young people to create the breadth that suits them best.

Whatever the critics may say, A-levels ain't broke, so there is no need to fix them. The improvements in hand will see them good for another 50 years.

Alan Smithers is professor and director of the Centre for Education and Employment Research at the University of Buckingham.